Uncontrollable aversive events, in contrast to controllable ones, have debilitating behavioral and physiological effects. The most extensively studied instances of these have been deficits in later learning and in the perception of pain. The importance of the psychological concept of the controllability of a stressor has been further supported by the fact that no such deficits occur when inescapable shock is preceded (an immunization effect) or followed (a therapy effect) by forcable exposure to escapable shock. Prior work in this area has focused on deficits in acquisition and performance of somewhat arbitrary responses in very contrived situations. In contrast, the proposed research utilizes laboratory procedures to study how animals react to controllable versus uncontrollable stress in terms of their more ethological or species-typical patterns of behavior. Using this approach, I have shown that inescapable (but not escapable) shock reduces aggression and increases defense in dominant colony rats when confronted by intruders. In a similar vein, only when mothers were given uncontrollable shock was there an interference in their subsequent caretaking behaviors. Most of the proposed experiments use a variant of the colony setting to answer the following questions: (1) Will immunization and therapy treatments, using escapable shock, eliminate the disruption that inescapable shock has on male aggression and maternal caretaking? (2) What effects do these decrements in maternal behaviors have on the offspring's later physical, sensory, motivational, and cognitive development? (3) Does inescapable stress also attenuate maternal protective attacks against colony intruders? (4) Do animals that experience repeated defeats, as intruders in male colonies, share many of the same behavioral and physiological dysfunctions as those given inescapable shock? (5) Does engaging in defensive posturing during inescapable shock prevent subsequent interference in ethological behaviors, and could this type of coping behavior be used to produce immunization and therapy effects? In attempting to answer these questions, this research will utilize experimental, observational, comparative, and pharmacological techniques; and it should enable us to learn more about how the concept of experiential control interrelates with ethological and physiological coping reactions to stress.